1. Field of the Invention
This invention relates to electro-acoustic transducers, and more particularly, but not exclusively, to relatively small loudspeakers for use in headphones. The invention is also applicable to loudspeakers of other sizes and for other purposes, and also to microphones.
2. Description of the Prior Art
Generally, a relatively small electro-acoustic transducer such as a loudspeaker for use in headphones includes a magnetic circuit and a diaphragm which comprises a dome-shaped central portion and a ring-shaped peripheral portion to be fixed to a frame. A voice coil is fixed to the diaphragm where the central and peripheral portions of the diaphragm meet, and is disposed in an air gap formed in the magnetic circuit.
Lead wires for the voice coil extend radially along the undersurface to the peripheral portion of the diaphragm and are bonded thereto by a suitable adhesive. Beyond the adhesive, unsupported portions of the lead wires are bent at right angles at or near the periphery of the diaphragm in order to be connected to terminals provided on an outside surface of the frame.
When the diaphragm vibrates with a large amplitude, it is not uncommon for the lead wires to snap. This is because the portions of the lead wires fixed to the peripheral portion of the diaphragm move together with the diaphragm, but the bent portions of the lead wires are not supported and moreover are bent at right angles, so that after a time the wire suffers from metal fatigue and may become brittle and snap. The radial disposition of the lead wires also causes problems as they contact the peripheral portion of the diaphragm when the diaphragm vibrates with large amplitude, and this generates noise.